1
1
23
1
1
0
z
D
2
z
N
N
)
z
(
H
-
-
-
+
=
Digital Microphone Input/Decimation Filter
2.3.3.1.2 User Programmable Filters
Depending on the selected processing block, different types and orders of digital filtering are available. A
1st-order IIR filter is always available, and is useful to efficiently filter out possible DC components of the
signal. Up to 5 biquad section or alternatively up to 25-tap FIR filters are available for specific processing
blocks. The coefficients of the available filters are arranged as sequentially indexed coefficients in two
banks. If adaptive filtering is chosen, the coefficient banks can be switched on-the-fly. For more details on
adaptive filtering see
below.
The coefficients of these filters are each 24-bits wide, in two's-complement and occupy 3 consecutive 8-bit
registers in the register space. For default values please see
.
2.3.3.1.2.1 1
st
Order IIR Section
The transfer function for the first order IIR Filter is given by
(2)
The frequency response for the 1
st
order IIR Section with default coefficients is flat at a gain of 0dB.
Details on coefficient default values are given in
.
Table 2-6. First-Order IIR Filter Coefficients
Filter
FIlter
Coefficient Left Channel
Coefficient Right Channel
Coefficient
N0
C4 (Pg 8,Reg 24,25,26)
C36 (Pg 9,Reg 32,33,34)
1
st
Order IIR
N1
C5 (Pg 8,Reg 28,29,30)
C37 (Pg 9,Reg 36,37,38)
D1
C6 (Pg 8,Reg 32,33,34)
C39 (Pg 9,Reg 40,41,42)
27
SLAU434 – May 2012
TLV320DAC3203 Application
Copyright © 2012, Texas Instruments Incorporated